What is the approach to diagnosing and treating pediatric strabismus?

Approach to Pediatric Strabismus Diagnosis and Treatment

Early diagnosis and prompt treatment of pediatric strabismus are essential because binocular vision can degrade rapidly in young children, resulting in suppression, amblyopia, and anomalous retinal correspondence—making timely intervention critical for preserving visual function and quality of life. 1

Key Terminology

• Esotropia (ET): Inward deviation of the eye ("crossed eyes") 1
• Exotropia (XT): Outward deviation of the eye ("wall-eyed") 1
• Intermittent deviation (X(T) or E(T)): Misalignment present only part of the time 1
• Constant deviation: Misalignment present at all times 1
• Phoria: Latent deviation controlled by fusion, only manifest when fusion is disrupted 1
• Comitant strabismus: Deviation remains constant in all gaze positions 2
• Accommodative esotropia: Esotropia driven by uncorrected hyperopia 1, 3

Diagnostic Approach

Initial History

Obtain detailed onset characteristics including age at onset, frequency of deviation, which eye deviates, direction of deviation, and whether diplopia or compensatory head postures are present. 1

Critical historical elements include: 1

• Date of onset and frequency of ocular misalignment
• Which eye is deviated and in what direction
• Presence or absence of diplopia, squinting, or closing one eye
• Review of photographs/videos showing the deviation
• Birth history: gestational age, birth weight, prenatal exposures (alcohol, tobacco, drugs) 1
• Family history of strabismus, amblyopia, or need for corrective eyeglasses 1
• Developmental milestones and any neurodevelopmental concerns 1
• History of head trauma or symptoms suggesting increased intracranial pressure 1

Comprehensive Examination

The examination must include visual acuity testing, binocular alignment assessment at distance and near, extraocular motility evaluation, cycloplegic refraction, and funduscopic examination to rule out structural abnormalities. 1

Sensory Testing (Perform BEFORE Motor Testing)

Complete sensory testing before any occlusion or alignment testing, as dissociating the eyes can disrupt binocular status and yield inaccurate results. 1

• Stereopsis testing: Use Preschool Randot, Randot Test, Random-Dot E, TNO, Frisby, Stereo Fly, or Lang tests 1
• Worth 4-Dot Test: Assesses central fusion at distance and peripheral fusion at near 1
• Indicators of poor prognosis: Reduced stereoacuity, suppression, or lack of fusion 1

Motor Testing and Alignment Assessment

Use prism and alternate cover test to measure the total deviation for surgical planning, and simultaneous prism-and-cover test to measure manifest deviation under binocular viewing conditions. 1

Key measurements include: 1

• Binocular alignment at distance and near in primary gaze
• Alignment in up, down, and horizontal gaze positions
• Testing both with and without refractive correction
• Extraocular muscle function: versions (binocular) and ductions (monocular)
• Detection of A or V patterns, oblique muscle dysfunction
• Assessment for dissociated vertical or horizontal deviations

Detection of Nystagmus

Document any manifest, latent, or manifest-latent nystagmus, as this commonly coexists with infantile esotropia and affects surgical planning, particularly regarding head posture. 1

• Manifest nystagmus: Present constantly, may be horizontal, vertical, or torsional 1
• Latent nystagmus: Appears only with monocular occlusion, reverses direction with change in fixation 1
• Manifest-latent (fusion maldevelopment) nystagmus: Present binocularly but worsens with occlusion 1

Cycloplegic Refraction

Adequate cycloplegia is mandatory for accurate refraction in children due to their increased accommodative tone; this is the single most important test for identifying accommodative esotropia. 1, 4, 3

• Perform cycloplegic retinoscopy or autorefraction 1
• Hyperopia ≥+1.00 D should be fully corrected as first-line treatment for esotropia 4, 3
• Dynamic retinoscopy before cycloplegia can assess accommodative function 1

Funduscopic Examination

Complete dilated fundus examination to identify retinal or optic nerve abnormalities that may cause sensory strabismus. 1

Red Flags Requiring Urgent Evaluation

Immediately consider restrictive, paralytic, or neurologic causes—especially head trauma or increased intracranial pressure—as acute onset comitant esotropia may indicate pontine or cerebellar tumor. 1, 5

Treatment Approach

Rationale for Treatment

Treatment aims to promote binocular vision, improve visual function in each eye, prevent amblyopia, and normalize appearance to enhance self-image and social interactions—all of which significantly impact quality of life. 1, 6

Evidence demonstrates: 1, 6

• Strabismus reduces health-related quality of life in preschool children
• Children express negative feelings about strabismus starting at age 5 years
• Teachers rate children with strabismus more negatively
• Strabismus reduces employment opportunities due to stigma and bias
• Parents of children with strabismus experience reduced quality of life

Treatment Algorithm

Step 1: Optical Correction (First-Line for Esotropia)

For any child with esotropia and hyperopia ≥+1.00 D, prescribe full cycloplegic refractive correction immediately as this successfully realigns most cases of accommodative esotropia. 4, 3

• Correct hyperopic refractive error as quickly as possible, as younger children lose binocular vision rapidly 1, 4
• Wait several weeks after prescribing glasses to assess alignment improvement 3
• Repeat cycloplegic refraction if esotropia persists despite optical correction 3

Step 2: Amblyopia Treatment

Initiate amblyopia treatment before surgery using occlusion therapy (patching) or atropine penalization, as treating amblyopia may alter the angle of strabismus and increase likelihood of good postoperative binocularity. 1, 4, 3

• Amblyopia is present in 26% of esotropia cases and 16% of exotropia cases 7
• Esotropia is more likely than exotropia to be associated with amblyopia 7
• For smaller angle deviations, consider prisms 1

Step 3: Surgical Intervention

Surgery is indicated when deviation is constant, large (typically >40 prism diopters), fails to respond to optical correction, or when severity precludes effective amblyopia treatment. 4, 3

Timing considerations: 4, 3

• Infantile esotropia: Early surgical correction before age 2 years improves sensory outcomes by minimizing duration of constant esotropia (though no evidence shows improved motor outcomes compared to later surgery)
• Accommodative esotropia: Surgery only after optical correction trial fails
• Intermittent exotropia: Surgery when control deteriorates, stereoacuity reduces, or suppression develops 1

Special Considerations for Exotropia

Children with intermittent exotropia require assessment of fusional control at both distance and near, with documentation of the proportion of waking time the eyes are misaligned and ability to control the deviation. 1

• Record as constant exotropia (XT), intermittent exotropia (X(T)), or exophoria (X) 1
• Indicators of progression: worsening control, reduced stereoacuity, development of suppression 1
• Only 15% of children aged 3-10 years show deterioration over 3 years of observation 1
• Surgery improves quality of life in children with intermittent exotropia 1

Age-Specific Management

Infants (0-6 Months)

Intermittent eye misalignment during the first 3 months is normal visual development; however, esotropia appearing before 6 months requires urgent referral to pediatric ophthalmology to preserve binocular vision. 4, 8

• Ophthalmological evaluation necessary if strabismus persists beyond 3-4 months, becomes constant, or associated concerns develop 4, 8
• Infantile esotropia carries high risk for amblyopia development 4

High-Risk Populations Requiring Vigilant Monitoring

Risk factors include: 8, 7

• Family history of strabismus (present in 25% of cases)
• Premature birth, especially birth weight <2000 grams
• Neurodevelopmental impairment
• Significant hyperopia
• Low Apgar scores
• Exposure to smoking or alcohol in utero
• Craniofacial or chromosomal anomalies
• History of neonatal intensive care unit stay
• Epilepsy (present in 10% of strabismus cases)

Follow-Up and Monitoring

Children with good fusional control of intermittent exotropia without amblyopia should be examined every 6-12 months, with frequency reduced by age 7-10 years; children with esotropia or poor control require more frequent monitoring. 1

Follow-up evaluation includes: 1

• Frequency of any deviation
• Adherence to treatment plan
• Ocular motility assessment
• Update of refractive correction if needed

Common Pitfalls to Avoid

• Never initiate patching as sole initial intervention without ruling out accommodative esotropia correctable with eyeglasses alone 3
• Never proceed directly to botulinum toxin or surgery without first attempting optical correction for esotropia 3
• Never perform motor testing before sensory testing, as occlusion dissociates binocular status 1
• Never delay treatment in young children, as binocular vision degrades rapidly 1, 4
• Never assume intermittent deviation beyond 4 months is normal—this requires evaluation 4, 8